ENS 47130
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ENS Event | |
|---|---|
11:17 Aug 6, 2011 | |
| Title | Initiation of Technical Specification Required Shutdown |
| Event Description | On August 6, 2011, Reactor Protection System (RPS) power supply 1B failed resulting in a partial loss of power to Primary Containment Isolation System (PCIS) groups and an invalid actuation of those PCIS groups. PCIS groups 1 and 2 received partial isolation signals with no subsequent system isolations, as designed. PCIS group 3, 6, and 8 received partial isolation signals with resulting system isolations, also as designed. The combination of loss of RPS 1B and PCIS group 6 isolation resulted in the isolation of the Drywell Floor Drain Sump and the Drywell Continuous Atmospheric Monitor for both particulate and gaseous activity. Thus, both means of automatic monitoring of Reactor Coolant System leakage became inoperable. Unit 1 entered Technical Specification Limiting Condition for Operation (LCO) 3.4.5.D (all required leakage detection systems inoperable) and immediately entered LCO 3.0.3 as required.
At the time of occurrence, RPS 1A was being supplied from its alternate source for scheduled maintenance. Thus, the alternate source was not available to RPS 1B. Unit 1 entered LCO 3.0.3 at 0524 [CDT], 'Initiate actions within one hour to place the unit in MODE 2 within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />; MODE 3 within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />; and MODE 4 within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />.' At 0617, Unit 1 began reducing reactor power to comply with LCO 3.0.3. This event requires a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> report IAW 50.72(b)(2)(i), 'The initiation of any nuclear plant shutdown required by the plant's Technical Specifications.' The PCIS isolations which occurred at 0524 CDT are also reportable within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> per 10CFR 50.72(b)(3)(iv)(A) 'Any event or condition that results in a valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B)(2), 'General Containment Isolation signals affecting containment isolation valves in more than one system or multiple main steam isolation valves (MSIVs)], except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.' This event also requires an LER within 60 days per 10CFR 50.73(a)(2)(iv)(A). The event time for the PCIS isolations is 0524 CDT. The NRC resident inspector has been notified. Service Request 412927 was initiated in the Corrective Action Program.
Browns Ferry restored power to the 1B Reactor Protection System power supply at 1208 CDT, reset all isolations and exited LCO 3.0.3. The licensee plans to return the unit to full power. The licensee notified the NRC Resident Inspector. Notified R2DO (Binoy Desai). |
| Where | |
|---|---|
Browns Ferry  Alabama (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-0.53 h-0.0221 days <br />-0.00315 weeks <br />-7.25994e-4 months <br />) | |
| Opened: | William Baker 10:45 Aug 6, 2011 |
| NRC Officer: | Ryan Alexander |
| Last Updated: | Aug 6, 2011 |
| 47130 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (98 %) |
| After | Power Operation (97 %) |
Browns Ferry with 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
WEEKMONTHYEARENS 569902024-02-24T08:19:00024 February 2024 08:19:00
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2018 16:58:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Control Valve Closure ENS 531622018-01-10T15:28:00010 January 2018 15:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Control Valve Fast Closure Scram Signal ENS 526482017-03-29T23:44:00029 March 2017 23:44:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram Initiated During Startup ENS 518782016-04-22T18:59:00022 April 2016 18:59:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Partial Loss of Power Experienced During Electrical Bus Transfer ENS 513332015-08-20T15:32:00020 August 2015 15:32:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of an Emergency Diesel Generator on Low Bus Voltage ENS 512312015-07-14T22:15:00014 July 2015 22:15:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown ENS 504042014-08-26T22:30:00026 August 2014 22:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Generator Neutral Overvoltage Causes a Reactor Scram ENS 502652014-07-10T09:45:00010 July 2014 09:45:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown ENS 502072014-06-17T22:29:00017 June 2014 22:29:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Shutdown Due to Loss of a and B Control Bay Chiller Trains ENS 500902014-05-06T13:30:0006 May 2014 13:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Low Reactor Water Level During Instrument Testing ENS 499282014-03-19T03:52:00019 March 2014 03:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Failure to Control Main Turbine Moisture Separator Level ENS 488292013-03-19T09:02:00019 March 2013 09:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Lowering Condenser Vacuum ENS 488222013-03-14T13:00:00014 March 2013 13:00:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unit 2 Shutdown Required by Technical Specifications Due to Inoperable Rcic ENS 487822013-02-25T19:13:00025 February 2013 19:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Automatic Scram Due to a Turbine Trip from a Loss of Condenser Vacuum ENS 489042013-02-11T11:13:00011 February 2013 11:13:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Initiation of Reactor Core Isolation Cooling System ENS 486232012-12-22T17:52:00022 December 2012 17:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Loss of Power to the Reactor Protection System ENS 479722012-05-29T08:31:00029 May 2012 08:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Main Generator Load Reject Signal ENS 479552012-05-24T11:39:00024 May 2012 11:39:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram During Startup ENS 479422012-05-22T07:49:00022 May 2012 07:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram Due to Reactor Protection System Being De-Energized ENS 472992011-09-28T09:14:00028 September 2011 09:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to a Turbine Trip ENS 471302011-08-06T11:17:0006 August 2011 11:17:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Initiation of Technical Specification Required Shutdown ENS 468722011-05-22T22:37:00022 May 2011 22:37:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Reactor Protection System (Rps) Actuation Signal - Scram Discharge Volume (Sdv) High Water Level ENS 468052011-05-02T11:26:0002 May 2011 11:26:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation Due to a Emergency Diesel Generator Output Breaker Trip ENS 468012011-04-29T04:38:00029 April 2011 04:38:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Primary Containment Isolation System Actuation Due to Loss of Power from a Diesel Generator ENS 467132011-03-30T20:42:00030 March 2011 20:42:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Initiated ENS 465112010-12-26T22:20:00026 December 2010 22:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to High Vibration on Main Generator Exciter ENS 459902010-06-09T08:31:0009 June 2010 08:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Closure of Main Steam Isolation Valves ENS 458882010-04-30T21:48:00030 April 2010 21:48:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Light Socket Short Causes Isolation Systems to Actuate ENS 457282010-02-26T01:35:00026 February 2010 01:35:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Rhr Inoperability ENS 453912009-09-30T04:23:00030 September 2009 04:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Unit 2 Manually Scrammed After Trip of an Operating Condensate Pump and Rapidly Lowering Rvwl ENS 452902009-08-24T23:50:00024 August 2009 23:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Condensate Booster Pump Trip Resulting in a Manual Reactor Scram ENS 451242009-06-11T20:55:00011 June 2009 20:55:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unit 2 Initiated a Tech Spec Required Shutdown Due to a Rise in Unidentified Drywell Leakage ENS 448602009-02-18T09:51:00018 February 2009 09:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip Due to Power Load Unbalance Signal on Main Generator Resulting in Reactor Scram ENS 448542009-02-16T11:13:00016 February 2009 11:13:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Loss of Stator Cooling Water ENS 445402008-10-05T03:08:0005 October 2008 03:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Following Reverse Power Signal on Main Generator ENS 441872008-05-05T08:32:0005 May 2008 08:32:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Power to Esf Buses During Transfer of Offsite Power Source ENS 438782008-01-01T03:40:0001 January 2008 03:40:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 3 Automatic Scram Due to Main Generator Load Reject Signal ENS 437182007-10-12T13:02:00012 October 2007 13:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Trip ENS 436132007-09-03T07:14:0003 September 2007 07:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Electro-Hydraulic Control (Ehc) System Leak ENS 435602007-08-11T22:51:00011 August 2007 22:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Scram Due to Neutron Monitoring Trip Signal ENS 434142007-06-09T16:00:0009 June 2007 16:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due Turbine Trip as a Result of High Moisture Separator Reheater Tank Level ENS 433812007-05-24T07:11:00024 May 2007 07:11:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Electro-Hydraulic Control (Ehc) System Leak ENS 430922007-01-11T14:16:00011 January 2007 14:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram When Turbine Output Breakers Opened ENS 428132006-08-30T03:25:00030 August 2006 03:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Electro-Hydraulic Oil Leak ENS 427872006-08-19T16:05:00019 August 2006 16:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram of Unit 3 Due to the Loss of Both Reactor Recirculation Pumps ENS 421022005-10-31T19:18:00031 October 2005 19:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Trip of Main Turbine ENS 419972005-09-17T16:29:00017 September 2005 16:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to Maintenance ENS 418962005-08-05T22:08:0005 August 2005 22:08:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Rps Actuation Due to Low Reactor Water Level Caused by Loss of Reactor Feed Pumps ENS 418612005-07-22T08:16:00022 July 2005 08:16:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown T/S Shutdown Due to Dc Subsystem Declared Inoperable ENS 415952005-04-13T15:53:00013 April 2005 15:53:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Rps Actuation Due to an Invalid Atws Logic Actuation ENS 414042005-02-11T22:29:00011 February 2005 22:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to a Load Rejection ENS 412192004-11-23T16:02:00023 November 2004 16:02:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Turbine Trip ENS 408622004-07-11T03:35:00011 July 2004 03:35:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to an Upscale Trip on Intermediate Range Monitors ENS 408582004-07-09T03:32:0009 July 2004 03:32:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to a Turbine Generator Load Rejection Signal 2024-02-24T08:19:00 | |
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